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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
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    <title>Document</title>
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        * {
            margin: 0;
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        div {
            width: 600px;
            height: 400px;
            margin: 50px auto;
            border: 1px solid black;
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        div h1 {
            text-align: center;
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<body>
    <div>
        <h1 style="background-color:red;">我们的世界</h1>
    </div>
</body>

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